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PubMed1987

Poly(hydroxy acids) in drug delivery.

Poly(hydroxy acids) so far have been examined for use in drug delivery in limited number, while the advantageous use of the polymers has been recognized due to their biodegradability and biocompatibility. Homo- and copolymers of lactic acid and glycolic acid have been studied in drug delivery by many workers, while homo- and copolymers of epsilon-caprolactone have been studied by only one group of workers. Although poly-hydroxybutyric acid had been found to be a naturally occurring polymer, examination as to the use of the polymer in drug delivery is rather recent and reports are still limited. In the present article, the use of poly(hydroxy acids) including homo- and copolymers of lactic acid and glycolic acid, polycaprolactone, and poly-beta-hydroxybutyric acid in drug delivery is reviewed. Physicochemical properties, biodegradability, and biocompatibility of the polymers, and evaluations in vitro and in vivo of specific dosage forms using the polymers, are included. The most recent work in our laboratories on the use of polyactic acid and poly-beta-hydroxybutyric acid is also included.

Biocompatible Materials↗
PubMed1986

Direct measurement of poly(beta-hydroxybutyrate) in a pseudomonad by solid-state 13C NMR.

Four narrow lines are observed in the high-resolution cross-polarization magic-angle spinning 13C NMR spectra of intact, lyophilized samples of Pseudomonas sp. LBr, in addition to the broader lines normally associated with bacterial cellular material. These narrow lines arise from poly(beta-hydroxybutyrate). The cellular carbon contained in this storage material can be measured quantitatively and nondestructively from the solid-state NMR spectra. We find that cells starved for phosphorus store up to 50% of their total carbon as poly(beta-hydroxybutyrate). When such cells are used to inoculate medium containing a source of phosphorus, all of the poly(beta-hydroxybutyrate) is metabolized by the time the culture has reached midlogarithmic growth phase.

Carbon Isotopes↗
PubMedDate not supplied

Isolation and metabolism of glycogen and poly-betahydroxybutyrate in Nocardia asteroides at different developmental stages.

Sudanophilic and iodine-staining cytoplasmic granules were isolated at various developmental stages during growth of Nocardia asteroides (strain 55) and identified as poly-beta-hydroxybutyrate (PHB) and glycogen granules, respectively. During growth in nutrient broth containing 1% glucose, maximal accumulation of PHB and glycogen granules, up to 10 and 20% respectively, of its dry-weight was obtained in the filamentous cells at 16 h just prior to the onset of cell fragmentation during the stationary phase. The decrease of the cytoplasmic granules was concomitant with fragmentation of the cells to rod-like and spherical cells, suggesting that the polymers may serve as carbon and energy source during morphogenesis. Both granules were detected in the three cell-forms. At higher concentrations of glucose (4%) more glycogen granules (9 times) accumulated than PHB (4 times) and glycogen hydrolysis was also faster than that of PHB, suggesting preferences of glycogen over PHB as energy and carbon source under this growth condition. Growth and biosynthesis of granules were significantly reduced by very high glucose concentration (10%) and the usual pleomorphic developmental stages were reduced to a dimorphic life cycle. Thus, biosynthesis of both granules and morphogenesis are under catabolite repression. Both polymers were also found in N. brasiliensis and N. otitidis-caviarum, indicating that cytoplasmic accumulation of multiple granules is common in the genus.

Cytoplasmic Granules↗
PubMedDate not supplied

[Lipids of the luminescent bacteria Photobacterium mandapamensis].

The composition of lipids was studied in the luminescent bacterium Photobacterium mandapamensis under the conditions of maximal luminescence. The synthesis of total lipids and poly-beta-hydroxybutyric acid (PHBA) was investigated in dynamics under the conditions of batch cultivation. The major class of lipids was polar lipids (84.3%) represented by phospholipids (phosphatidyl ethanolamine, phosphatidyl glycerol, cardiolipin, lysocardiolipin, lysophosphatidyl ethanolamine) and a minor nonidentified phospholipid. The fraction of neutral lipids was represented mainly by free fatty acids (about 5%), tri- and diglycerides (in trace amounts), and two nonidentified classes, apparently, hydrocarbons and waxes. A correlation was established between the luminescence of the bacterium and the content of PHBA.

Hydroxybutyrates↗
PubMed1994

Biosynthesis of poly-3-hydroxybutyrate in the luminescent bacterium, Vibrio harveyi, and regulation by the lux autoinducer, N-(3-hydroxybutanoyl)homoserine lactone.

Poly-3-hydroxybutyrate (PHB), a biopolymer of important commercial applications, is found in a wide range of Gram-negative and Gram-positive bacteria and cyanobacteria. The present study has resulted in the identification of PHB in the luminescent marine bacteria, Vibrio harveyi, in spite of it being previously classified as PHB-negative. PHB granules with distinct membranes were detected by electron microscopy after fixation and staining of V. harveyi cells with malachite green. Analyses by gas chromatography, nuclear magnetic resonance, infrared, and ultraviolet spectroscopy clearly established the presence of PHB. The synthesis of PHB in V. harveyi was found to be under cell density regulation with the levels increasing from 0 (< 0.2) to 26 mg of PHB/g of dry cell weight during growth in a manner analogous to the induction of luminescence in this bacteria. Moreover, synthesis of PHB in V. harveyi was shown to be controlled by the lux autoinducer, N-(3-hydroxybutanoyl)homoserine lactone, providing not only a potential link between luminescence and PHB production but also showing that the lux autoinducer acts as a general signal transductant. These results have also extended the role of homoserine lactones in metabolic regulation to include the control of synthesis of potential energy reserves.

4-Butyrolactone↗
PubMedDate not supplied

[Poly-(3-hydroxybutyrate) granules in Bacillus megaterium. Isolation and analysis of associated proteins].

Bacillus megaterium accumulates poly-(3-hydroxybutyrate) (PHB) as a reserve material in intracellular granules. In this work we described a method for the preparation of PHB granules from B. megaterium PV447 and the analysis by polyacrylamide gel electrophoresis of the associated proteins. By comparison with another species a function is proposed for some of these proteins.

Acyltransferases↗
PubMed1996

[Bio-absorbable synthetic polyesters and tissue regeneration. A study of three-dimensional proliferation of ovine chondrocytes and osteoblasts].

The tissue engineering area henceforth calls more and more for bioabsorbable substrata made of biopolymers (collagen, laminin...) or polymers (PLA, PLGA, PGA...) to realize the three-dimensional culture of tissue equivalents. The poly (beta-hydroxybutyrate-beta-hydroxyvalerate), a biopolymer considered as being biodegradable and biocompatible, has been recently introduced for orthopaedic biomaterials and regeneration purposes. In our study, a PHB/9% HV polymer was transformed into 3D foams, then applied to the culture 3D of ovine chondrocytes (fibrous rings & growth plates) and osteoblasts (periostum). Sponges made of bovine type I collagen were used as references. Orthopaedic cells were isolated, prepared and sown by simple injection to the geometrical center of the substrata, then incubated from 0 to 35 days by changing the culture medium all 4 days. Maximal densities were reached after 21 days: 18-24.10(6) cells/g for the chondrocytes, 8-10.10(6) cells/g for the osteoblasts. The cellular proliferation was more marked, with highest cell densities, for the collagen sponges. Laser confocal microscopy shows that the cellular diffusion take place throughout the entire volume of the porous artificial substrata. Future studies will allow to apply the porous bioabsorbable substrata to high-density cell cultures, to the tissue engineering and regeneration, for example for orthopaedic tissues: cartilage, fibrocartilage and bone.

Animals↗
PubMed1997

[A preliminary report on clinical application of biopoly ester ligament].

Sixty-one cases of fracture or dislocation were treated with France-made biopolyester ligament. They consisted of 18 cases of fracture of patella, 13 cases of fracture of olecranon, 8 cases of fracture of distal clavicle, 10 cases of dislocation of acromino-clavicular joint, 6 cases of separation of lower tibio-fibular joint, 3 cases of rapture of cruciate ligament and 3 cases of fracture of upper third of ulna with dislolcation of radial head. The follow-up period lasted from 3 to 12 months with an average of 7.3 months. The result showed that of the 56 follow-up cases, 49 were excellent and 7 were satisfactory. There was no redisplacement occured in this group. The Biopolyester ligament was believed to be a good and safe material for fractures or dislocations and was of good strength of extension and easy to use.

Adolescent↗